Photographic film



United States Patent 3,023,101 PHOTOGRAPHIC FILM Armin Ossenbrunner, Leverkusen, Hermann Schnell, Krefeld-Uerdingen, Helfried Klockgether and Julius Geiger, Leverkusen, and Joachim Freier, Krefeld- Uerdingen, Germany, assignors to Agia Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany No Drawing. Filed Dec. 27, 1957, Ser. No. 705,499 Claims priority, application Germany Dec. 31, 1956 2 Claims. (Ci. 9687) The present invention relates to photographic films and more particularly to new and improved photographic films comprising a light sensitive layer carried by a film support comprising a high-molecular polycarbonate.

It has already been proposed in our copending application Serial No. 577,362, filed April 4, 1956, now abandoned, to use as a support for light sensitive (radiation sensitive) layers films or foils produced form a linear high-molecular polycarbonate derived from di-monohydroxyaryl alkanes or mixtures of di-monohydroxylaryl alkanes and other dihydroxy compounds such as aliphatic, cycloaliphatic or aromatic dihydroxy compounds.

We have now found in further development of the above subject that photographic films with valuable properties are obtained by replacing the aforementioned polycarbonate in the film support at least partially by further linear high-molecular polycarbonates.

Such further thermoplastic polycarbonates of high molecular weight can be obtained by reacting dihydroxy diaryl sulphones or mixtures of dihydroxy diaryl sulphones with other biiunctional dihydroxy compounds according to German patent application No. F 17,168 Ive/39c (D.A.S. 1,007,996, published May 9, 1957) and from dihydroxy diaryl ethers or dihydroxy diaryl thioethers or from mixtures of the said compounds with other dihydroxy compounds according to German patent application Nos. F 21,459 IVb/39c and F 21,662 IVc/39c.

vFurther suitable polycarbonates are those which are derived from mixtures of aliphatic and/ or cycloaliphatic dihydroxy compounds with at least one aromatic dihydroxy compound other than the above cited aromatic dihydroxy compounds.

In the dihydroxydiaryl sulphones used for forming the polycarbonates, the aryl residues can be the same or different. The aryl residues can furthermore carry hydrogen atoms or substituents which are incapable of taking part in the reaction to polycarbonates, e.g. the halogens and alkyl groups such as ethyl, methyl, propyl or tertiary butyl.

As examples of dihydroxydiaryl sulphones of the specified type, the following may be mentioned:

4,4 dihydroxydiphenylsulphone, 2,2 dihydroxydiphenylsulphone, 3,3-dihydroxydiphenylsulphone, 4,4'-dihydroxy-2,2'-dimethy1-diphenyl-sulphone, 4,4'-dihydroxy- 3,3 dimethyl-diphenyl-sulphone, 2,2-dihydroxy-4,4-dimethyl-diphenyl-sulphone and 2,2-dihydroxy-1,1-dinaphthyl-sulphones.

As examples of the other dihydroxy compounds which may be used in admixture with the dihydroxydiaryl sulphones if desired, there may be mentioned the following: ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, the corresponding thioglycols, dior polyglycols obtained from propylene oxide-1,2, propanediol- 1,2, propanediol-l,3-butanediol- 1,3, butanediol- 1,4, 2- methyl propanediol-l,3, pentanediol-1,5, 2-ethylpropanediol 1,3, hexanediol 1,6, octanediol 1,8, 2 ethylhexanediol-1,3 and decanediol-1,10; cyclohexanediol-1,4, cyclohexanediol-l,2, o-, p-, or m-xylene glycol, 2,2-(4,4.- dihydroxy-dicyclohexyl)propane, 2,6-dihydroxy dicahydronaphthalene, hydroquinone, resorcinol, pyrocatechol, 4,4 dihydroxydiphenyl, 2,2'-dihydroxydiphenyl, 1,4 di- 2 hydroxynaphthalene, 1,6 -dihydroxynaphthalene, 2,6-di hydroxynaphthalene, 1,2 dihydroxynaphthalene, 1,5 dihydroxyanthracene, 2,2'-dihydroxydinaphthalene-1,1, and 0-, m-, or p-hydroxybenzylalcohol. Di-monohydroxyarylalkanes as disclosed in copending application Serial No. 577,362, filed April 4, 1956, and in British specification No. 772,627, such as di-(p-hydroxyphenyl)-methane, 2,2- di-( p-hydroxyphenyl) -propane, 1, l -di-(p-hydroxyphenyl) cyclohexane, 1,1-di-(p-hydroxy-m-methylphenyl) cyclohexane, 2,2-di (o-hydroxy-p-tert.-butylphenyl) propane and 3,4-di-(p-hydroxy-phenyl)-hexane and 1,1-di-(p-hydroxy-phenyl)-1-phenyl-ethane, furthermore methane derivatives which carry besides two hydroxylaryl groups, a further alkyl residue with at least two, and a second alkyl residue with one or more carbon atoms, e.g. 2,2-di- (p hydroxyphenyl)-butane, 2,2 di-(p hydroxypheny1)- pentane, 3,3-di-(p-hydroxyphenyl)-pentane, 2,2-di-(phydroxyphenyl) 3 methylbutane, 2,2-di (p hydroxyphenyl)-hexane, 2,2-(1i (p-hydroxyphenyl)-4-methylpentane, 2,2-di-(p-hydroxyphenyl)-heptane, 4,4-(p-hydroxyphenyl)-heptane and 2,2-di-(p-hydroxyphenyl)-tridecane.

The polycarbonates may be produced if, for example, bis-chloro-carbonates of dihydroxy diaryl sulphones or mixture thereof with the aforementioned dihydroxy compounds, are condensed with dihydroxy diaryl sulphones, or mixtures thereof with other dihydroxy compounds. These condensations are suitably brought about in the presence of inert solvents and acid binding agents such as tertiary amines as described for analogous processes in British specification No. 772,627.

A further method of carrying out the process consists in passing phosgene either into an aqueous alkali solution or suspension of the dihydroxy diaryl sulphone, optionally in the presence of other dihydroxy compounds and inert solvents, or into a solution or suspension of these materials in an inert solvent optionally in the presence of.

acid-binding agents such as tertiary amines also as described for analogous processes in British specification No. 772,627.

According to both methods of carrying out the process it is an advantage to accelerate the polycondensation by adding to the reaction mixture quaternary ammonium compounds in the form of their free bases or as salts.

Finally it is also possible to produce the polycarbonates by inter-esteriiying dihydroxy diaryl sulphones, optionally mixed with the aforementioned dihydroxy compounds and suitably in the presence of acidic or basic catalysts, with dialkyl or diaryl carbonates. The basic catalysts preferably used are suitably neutralised in the course of, or at the end of, the polycondensation by adding basebinding substances are especially suitable since an excess thereof can be removed, by evaporation or sublimation from the melt.

For the production of the polycarbonates derived from diphenyl ethers and -thioethers, diphenyl ethers and/or -thioethers may be used in which the two aryl radicals are the same or diiferent.

The aryl radicals may further carry substituents which are incapable of reacting during the conversion into the polycarbonates such as halogen, or alkyl groups such as the methyl-, ethyl-, propylor the tert. butyl group.

Suitable dihydroxy-diaryl ethers or -thioethers are, for example:

4,4'-dihydroxy-diphenyl ether, 4,4'-dihydroxy-2,2'-dimethyl diphenyl ether, 4,4-dihydroxy-3,3'-dimethy1diphenyl ether or their homologues, as well as 4,4-dihydroxydiphenyl sulphide, 4,4-dihydroxy-2,2-dimethyldiphenyl-sulphide, 4,4-dihydroxy-3,3-dimethyldiphenylsulphide and their homologues, The latter are readily obtainable by condensation of sulphur dichloride with the corresponding phenols.

The further dihydroxy compound which may be used in combination with the said ethers and thioethers may be the same as those disclosed above in connection with the production of polycarbonates derived from diaryl sulfones. The polycarbonates produced from the above ethers and thioethers or mixtures of said compounds with further dihydroxy compounds may be produced by the same methods as the polycar'bonates derived from diarylsulphones and mixtures of said sulphones with further dihydro compounds.

For the production of polycarbonates derived from mixtures of aliphatic and/or cycloaliphatic dihydroxy compounds with aromatic dihydroxy compounds other than the above dihydroxy diarylalkanes, dihydroxydiarylsulfones, and dihydroxydiarylethers and -thioethers there may be used the following aromatic dihydroxy compounds:

l-Iydroquinone, resorcinol, pyrocatechol, 4,4'-dihydroxydiphenyl, 2,2-dihydroxydiphenyl, 1,4-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 1,2. dihydroxynaphthalene, 1,5 dihydroxynaphthalene, 1,4-dihydroxyquinoline, 2,2-dihydroxydinaphthyl-1,1 and mor phydroxybenzyl alcohol. As aliphatic or cycloaliphatic dihydroxy compounds to be used according to the invention, there may be named: ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, thiodiglycol, ethylene dithiodiglycol, propanediol-1,2, propanediol-l,3, butanediol-1,3, butanediol-l,4, 2-methylpropanediol-L3, pentanediol-1,5, 2-ethylpropanediol-l,3, hexanediol 1,6, octanediol 1,8, 2-ethylhexanediol 1,3, decanediol-l,l0, cyclohexanediol-1,4, cyclohexanediol-l,2, o-, mor p-xylylene glycol, 2,2-(4,4'-dihydroxydichlor0- heXyD-propane, 4,4-dihydroxydicyclohexyl methane and 2,6-dihydroxy-decahydronaphthalene.

The transformation of the foregoing dihydroxy compounds into high molecular polycarbonates can be carried out by the methods disclosed above.

The' aforementioned polycarbonatcs derived from the disclosed sulphones, ethers and thioethers may be represented by way of example by the following formula:

in which R stands for one of the following bivalent radithe phenyl radicals of which may be substituted and It stands for a whole member preferably greater than 10. The mixed polycarbonates may contain the following in which R stands for the same radicals as R and for a substituted or unsubstituted phenylene radical and R" stands for any bivalent organic radical which is different from R whereby R" cannot be a diarylalkane radical in case that R is a phenylene radical, the total number of said units being preferably at least and the relative proportions of said units varying between about 1:30 and 30:1.

Since the polycarbonates to be used according to the invention dissolve satisfactorily in a number of low-boiling solvents, the foils can be manufactured by the conventional casting method on a band or drum machine, the advantages of this process, namely the production of a uniform thickness and optical clarity in transparency and surface, being fully maintained. The thoroughly dried raw material is dissolved in a stirrer mechanism,

4 preferably a high-speed stirrer, for example in methylene chloride to form a solution with a viscosity of about 30,000 to 60,000 cp. Small proportions of solvents with a higher boiling point, which do not have to be good solvents for the plastic (such as chloroform, propyl acetate or butyl acetate), can also be added. Depending on the quality which is required, the addition of small quantities of plasticisers such as tricresyl phosphate is advisable. After removal of the air, the solution is cast on a casting machine in the thickness which is required as for instance 0.05 to 0.3 mm. and at the speed which is usual for acetyl cellulose foils. If desired, the polyesters to be used according to the invention can also be worked into film in a manner known per se from the molten mass. it is of course possible for dyes or pigments also to be added to the solutions or melts of the polycarbonates prior to the shaping.

Before the light-sensitive layers are applied, preferably silver halide emulsion layers or layers of bichromated hydrophilic colloids or photographic auxiliary layers, such as antihalation layers, the binders of which consist of gelatine or other natural or synthetic film-forming hydrophilic colloid layers, the layer support is generally provided with suitable adhesive layers which can be produced by various methods. I

For example, prior to the application of hydrophilic colloid layers to the layer support, the latter can be treated with a solution which contains a mixed acetal of polyvinyl alcohol and aldehydes with water-solubilizing groups and aldehydes without water-solubilizing groups. This mixed acetal is soluble in organic solvents and has a strong swelling power in water. The treatment with the said solution can take place either alone or in combination with the production of further intermediate or rubbing layers. Vinyl chloride copolymers, such as for example copolymers of vinyl chloride and vinyl acetate or vinyl propionate, have proved highly suitable for the production of such further intermediate layers.

The aforementioned mixed acetals can be obtained by a conventional process, for example by heating the components for several hours in methanolic solution with sulphuric acid as catalyst. Examples of aldehydes with water-solubilizing groups are aromatic aldehydes which are substituted in the aromatic nucleus by carboxyl, sulphonic acid or hydroxy groups, for example benzaldehyde-Z-sulphonic acid, benzaldehyde-2,2-disulphonic acid and p-hydroxy benzaldchyde. Examples of aldehydes without water-solubilizing groups are araliphatic and aliphatic aldehydes, for example benzaldehyde, tolyl aldehyde, p-chlorobenzaldehyde and hydrocinnamaldehyde.

For the bonding action which is to be produced, it is of decisive importance that both the hydrophilic and the hydrophobic components shall be used. The degree of acetalisation can fluctuate within Wide limits, but the best results are produced with products in which 50-60% of all hydroxyl groups of the polyvinyl alcohol are acetalised. The most favourable ratio between aldehydes with Watersolubilizing groups and those without water-solubilizing groups depends upon the nature of the aldehydes. It has, however, been found that, in general, a molecular excess of aldehydes without water-solubilizing groups is necessary for the production of a sufficient degree of solubility in organic solvents.

For producing the intermediate layer, the mixed acetals are preferably dissolved in a proportion of 0.75 to 1.25% in a mixture of methanol and one or more other organic solvents, for example acetone, tetrahydrofurane or dioxane. For improving the bonding action, it is advisable to add a small proportion of a partially saponified copolymer of vinyl chloride and an organic vinyl ester, for example vinyl acetate, vinyl propionate or vinyl butyrate, for example, a partially saponified copolymer of vinyl chloride and vinyl acetate. These partially saponified copolymers are produced by known methods by saponification in methanol solution with sulphuric acid as catalyst, merely the organic ester groups being partially saponified. Suitable saponified copolymers contain approximately 45-70% by Weight of vinyl chloride, 5-30% by weight of vinyl hydroxide and 40% by weight of vinyl acetate or another organic vinyl ester such as vinyl propionate, vinyl butyrate or vinyl benzoate. Copolymers of vinyl chloride and a, B-unsaturated carboxylic acids or partially saponified copolymers of vinyl chloride'and esters of the aforementioned acids can alternatively be used. The coating is advantageously produced by one of the conventional dipping processes.

Furthermore, the layer support can be provided with a thin intermediate layer of vinyl chloride copolymers and nitrocellulose or organic cellulose esters, a further thin intermediate layer of cellulose esters arranged thereabove, and a thin layer containing gelatine as a third layer.

As vinyl chloride copolymers in the first layer, it is advantageous to use a copolymer of about 40 to 70 parts by weight of vinyl chloride with about 30 to 60 parts by weight of copolymerisable components, for example lower alkyl esters of unsaturated carboxylic acids and vinyl esters of lower fatty acids, such as methyl, ethyl, propyl, butyl esters of acrylic acid, methacrylic acid, crotonic acid or maleic acid, and also vinyl acetate, vinyl propionate or vinyl butyrate.

Examples of suitable cellulose esters are mixed esters of cellulose with acetic acid and fatty acids which contain 3-4 carbon atoms, for example cellulose acetopropionate and cellulose acetob'utyrate.

For the production of the first layer, the cellulose esters are advantageously used in proportions of 30-70% by weight, calculated on the total quantity of the polymers and cellulose esters.

For the subbing of the layer support, it is also possible to use auxiliary layers which consist essentially of gelatine and a partially hydrolysed copolymer of 40 to 60 parts by weight of vinyl chloride and 60 to 40 parts by weight of the above organic vinyl esters, this copolymer advantageously containing from 45 to 70% by Weight of vinyl chloride, 530% by weight of vinyl hydroxide and 10 to 40% by weight of organic vinyl ester. The proportion of gelatine with respect to the copolymer can fluctuate within wide limits; it is however advantageous to use a ratio of 2:3 parts by weight of gelatine to 3:2 parts of copolymer. Furthermore, hardening agents for the gelatine can be incorporated into this auxiliary layer, for example formaldehyde or glyoxal. The aforemendomed-components are dissolved in conventional organic solvents and the solutions are applied to the support by one of the known dipping processes.

Other suitable auxiliary layers consist for example of nitrocellulose and an epoxy resin, above which is applied a second layer of gelatine. An additional layer of nitrocellulose can be applied between the layer of nitrocellulose epoxide resin and the gelatine layer. It is advantageous to use epoxide resins which are obtained by reacting epichlorhydrin with the di-(monohydroxy-aryl)alkanes which are used for the production of the polycarbonates of the layer support disclosed above or in copending application Serial No. 577,362. Instead of using the epoxide resin, it is also possible to use a polycarbonate ester of a di-(monohydroxy-arylene)alkane, also in admixture with nitrocellulose. Conventional devices can be used for applying the intermediate layers.

The foils thus pretreated for coating with a hydrophilic colloid layer are coated with a photographic silver halide emulsion for other light sensitive colloid layers by one of the conventional methods.

A check of the film material coated With a pho-totechnical or other emulsion shows that the material is particularly outstanding because of its very good stability of shape, which enables it to meet the high-standards of the reproduction artj The strongly pronounced hydrophobic nature of the foil causes an extremely low water-absorption capacity and results in the film material being so little dependent on climatic conditions that these conditions can be ignored in practice.

Whereas a change in the relative air humidity by 10% at 20 C. (in a range between and 85% relative humidity) with photo-technical films consisting of acetyl cellulose leads to a change in the length of the film by about 0.10%, with the polycarbonate foil this change is only 0.02%.

For the same reasons, the change in length caused by the photographic processing is also very slight. This processing shrinkage is also less than 0.02% with a film material with a base of polycarbonate. It is also necessary to emphasise the extremely slight change in dimensions as the temperature rises as compared with photographic films on other layer supports.

The measurements set out in the following table were effected after the film material had been storedfor 24 hours at the temperatures indicated.

Percent change in length of a photographic film material with a base of- Temperature, C.

Acetvl Polycellulose carbonate 0. 02 p i0 0. 18 0. 02 6O 0. 33 0. 02 0. 50 0. 02

avoided, especially in the processing of large sizes; thus,

no defects need be expected in the copying.

The film material can be manufactured without any diificulty in such a way that it remains flat enough to' satisfy all requirements-in all processing stages, and this flatness is also maintained with various change in climatic conditions.

The possibilities of using the photo-technical film on a polycarbonate support are very numerous. For example, the foils thus prepared for coating with a hydrophilic colloid layer can be coated with emulsions of steep and ultra-steep gradations, such as are usual in the reproduction art, for the production of line and screen exposures. The empulsions used in the reproduction art for reproducing halftones can be made contrasty, brilliant or normal. All the said emulsions can be unsensitised, orthochromatic or panchromatic.

The new film support is also suitable for montage films, especially for intaglio and offset printing, because good register is also important in these cases. The present films. may also be used for multi layers color films, cine films, roll films and X-ray films.

Example 1 A polycarbonate is produced as follows: I 71.5 parts-oi phosgene are introduced with stirring at 20 C. within 2 hours into a mixture of 96.3 parts of 2,2-di-(p-hydroxyphenyl)propane, and 47.3 parts of 7 ganic solvent becomes highly viscous in about an hour. It is washed neutral with water in the kneading machine. After evaporating the solvents, a hard elastic colorless high molecular resin remains which is soluble for example in methylene chloride, chloroform, ethylene chloride, dioxane, tetrahydrofurane and dimethylformamide. 100 parts of said polycarbonate are dissolved in 600 parts of methylene chloride. The solution is deaerated by heating at 50 C. and thereafter it is cast to form a film of 0.1 mm. thickness. The film is treated on one side with the following subbing solution:

1 g. of polyvinyl alcohol mixed acetal of polyvinyl alcohol, benzaldenyde and sodium salt of benzaldehyde 2,4-disulp-honic acid, used in the molar ratio of 3:1; degree of acetalization: 57.3%.

20 cc. of methanol,

cc. of dimethyl formamide,

70 cc. of methylene chloride,

0.3 g. of a saponification product of a copolymer of vinyl chloride and vinyl acetate (1:1 by weight). The saponification products contain 65.7 percent by weight of vinyl chloride, 22.7 percent by weight of vinylhydroxide, 11.6 percent by weight of vinylacetate.

The film is then coated on the pretreated side with a cinematographic or a phototechnical silver halide emulsion, the binding agent of which is gelatine. The film has an excellent dimensional stability (shrinkage after processing 0.02 percent).

Example 2 The following polycarbonate is produced:

Into a solution of 192 grams (0.8 mol) of 2,2-(4,4'- dihyroxydiphenyl)-butane, 47 grams (0.2 mol) of 4,4- dihydroxy-diphenyl ether in 1640 grams of a 10 percent sodium hydroxide solution, 149 grams (1.5 mol) of phosgene are introduced upon the addition of 1 litre of methylene chloride, at C. in a nitrogen atmosphere within 2 hours. After the addition of 0.5 gram of triethylamine and 4 grams of sodium isopropyl-naphthalene sulphonate, a viscous paste is formed in the course of about 2 hours. It is washed out in a kneader first with water, then with dilute hydrochloric acid and again with water, comminuted and dried under vacuum. A colorless resilient plastic material is thus obtained having a softening interval of 205-225 C. and which is soluble e.g. in methylene chloride, benzene, toluene, cyclohexanone and dimethyl formamide. Said polycarbonate is dissolved in methylene chloride and cast to a film of 0.14 mm. thickness as explained in Example 1. For the subbing of the film the following solution is used:

9 g. of gelatine,

19 cc. of ethylene chlorohydrine,

cc. of phthalic acid anhydride (10 percent of methanolic solution),

100 cc. of acetone,

75 cc. of 1 percent methanolic solution of glyoxal,

450 cc. of methylene chloride,

150 cc. of methanol,

100 cc. of tetrachloroethane,

75 cc. of a 10 percent acetonic solution of a copolymer of 1 part by weight of vinylchloride and 1 part by weight of vinylacetate, which is saponified to a product of the following composition:

65.7 parts by weight of vinylchloride, 22.7 percent of vinylhydroxide, 11.6 percent by weight of vinyl acetate. On this pretreated film there is coated a customary photographic silver halide gelatine emulsion.

Example 3 For the production of the film support disclosed in any of the preceding examples there is used a polycarbonate which is produced according to one of the following prescriptions.

To a mixture of 11.75 parts of hydroquinone-bis-chlorocarbonic acid ester,

11.52 parts of 4,4-dihydroxy-dicyclohexyl-2,2-propane,

and

26.0 parts of absolute methylene chloride there are added dropwise with stirring at 0 C. within 35 minutes a solution of 11.85 parts of absolute methylene chloride. The mixture is stirred for a further 15 hours at room temperature; the methylene chloride solution is then washed with dilute hydrochloric acid and water, dried over sodium sulfate and the methylene chloride evaporated under reduced pressure. A tough elastic transparent colorless resin remains with a softening range of 270-275" C., soluble for example in methylene chloride, chloroform, pyridine, and dimethyl formamide.

To a mixture of 23.5 parts of hydroquinone-bis-chlorocarbonic acid ester, 6.2 parts of ethylene glycol, and 500 parts of dry benzene,

24 parts of dry pyridine are added dropwise with stirring at 8-10 C. After 8 hours stirring at room temperature the mixture, consisting of polycarbonate and pyridine hydrochloride, is filtered off and washed with dilute hydrochloric acid and then with water. After drying, a powdery thermoplastic resin is obtained, soluble e.g. in methylene chloride, cyclohexane and dimethylformamide and having a softening range of ZOO-220 C.

Example 4 For the production of the film support disclosed above, there is used a polycarbonate which is produced as follows: Into a solution of 109 grams (0.5 mol) of 4,4-di hydroxydiphenyl sulfide and 112 grams (0.5 mol) of 2,2- (4,4'-dihydroxydiphenyl)-propane in 1640 grams of a 10 percent sodium hydroxide solution, 149 grams (1.5 mol) of phosgene is introduced at 20 C. within 1% hours after the addition of 600 grams of methylene chloride. Upon addition of 0.5 gram of triethylamine and 4 grams of so dium isopropylnaphthalene sulfonate a viscous paste is formed in the course of 1 hour. It is Washed out in a kneader successively with water, dilute hydrochloric acid and again with water, comminuted and dried in vacuo. A colorless resilient plastic material is thus obtained having a softening interval of 240-260 C. and dissolving e.g. in methylene chloride, chloroform, benzene, cyclohexanone and dimethyl formamide.

As already pointed out above the polycarbonates disclosed herein may be used in admixture with each other or with the polycarbonates of the copending application Serial No. 577,362, filed April 4, 1956, which latter are also disclosed in British specification 772,627. The proportions within which these polycarbonates may be used to produce photographic film supports may vary within wide limits since these polycarbonates are compatible with each other in practically all proportions.

We claim:

1. Photographic material comprising a film of a high molecular weight linear film-forming thermoplastic polycarbonate as the support, a hydrop-hilic subbing layer, and a photographic silver halide emulsion layer, said polycarbonate consisting essentially of the units and in which R stands for a member selected from the group the phenyl radicals of which may be substituted, the total number of said units being at least 10, and the relative proportions of said units to each other varying between about 1:30 and 30:1, said hydrophilic subbing layer being selected from the group consisting of layers of (1) a mixture of gelatin and a film-forming, partially saponified vinyl chloride-organic vinyl ester copolymer, and (2) a mixture of a film-forming, partially saponified vinyl chloride-organic vinyl ester copolymer and a filmforming mixed acetal of polyvinyl alcohol with an aromatic aldehyde containing water-solubilizing groups and an aromatic aldehyde free of water-solubilizing groups.

2. The photographic material of claim 1 wherein the polycarbonate is prepared from 4,4'-dihydroxy-diphenyl sulfide, 2,2-(4,4'-dihydroxydiphenyl)-propane and phosgene.

References Cited in the file of this patent UNITED STATES PATENTS 2,698,240 Alles et al. Dec. 28, 1954 2,698,241 Saner Dec. 28, 1954 2,789,967 Reynolds et a1 Apr. 23, 1957 2,799,666 Caldwell July 16, 1957 2,874,046 Klockgether et al Feb. 17, 1959 

1. PHOTOGRAPHIC MATERIAL COMPRISING A FILM OF A HIGH MOLECULAR WEIGHT LINEAR FILM-FORMING THERMOPLASTIC POLYCARBONATE AS THE SUPPORT, A HYDROPHILIC SUBBING LAYER, AND A PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER, SAID POLYCARBONATE CONSISTING ESSENTIALLY OF THE UNITS 